Door construction for shielded room



p 1962 c R. SCHALLER, JR 3,055,969

DOOR CONSTRUCTION FOR SHIELDED ROOM Filed April 13, 1960 2 Sheets-Sheet l 13 Ha] I 116.2- H616 INVENTOR.

Se t. 25, 1962 c. R. SCHALLER, JR

DOOR CONSTRUCTION FOR SHIELDED ROOM 2 Sheets-Sheet 2 Filed April 15, 1960 FIG. 10

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lected; and it is to includes all technical equivalents which operate in a United States atent 3,055,969 Patented Sept. 25, 1962 3,055,969 DOOR CONSTRUCTION FOR SHIELDED ROOM larence Randall Schaller, Jr., Philadeiphia, Pa., assignor to Ace Engineering and Machine Company, Inc, Huntlngdon Valley, Pa., a corporation of Pennsylvania Filed Apr. 13, 1960, Ser. No. 21,975 Claims. (Cl. 174-35) This invention relates to a shielded enclosure adapted to exclude from the enclosure interfering radio-frequency energy whose source is external to the enclosure and to keep within the enclosure radio-frequency energy whose source is within the enclosure. My present invention is directed particularly to an improved door construction for a shielded enclosure. When my door is in closed position, positive electrical contact between door and door casing is obtained, thus assuring that the enclosure will function as an effective radio-frequency shield.

In my improved door construction, the use of wiper fingers is avoided. Thus, the tendency to bind and stick during opening and closing, which ordinarily attends doors employing wiper fingers, is avoided. My improved door opens and closes with ease, yet positive electrical contact between door and casing is obtained when the door is closed. Alignment problems are also greatly reduced when my construction is employed.

My invention will be best understood from a consideration of the following detailed description of a preferred embodiment as illustrated in the drawing in which:

-FIG. 1 is a front elevational view of my improved door;

FIG. 2 is a side elevational view, in section, along the line II-II of FIG. 1; FIG. 3 is a top elevational view in section along the line IIIIII of FIG. 1;

FIG. 4 is a detailed showing of the corner of the door;

FIG. 5 is a View of a portion of metal-cloth contact element which may be used to provide the good electrical contacts between the door and the door casing;

FIG. 6 is a view similar to that of FIG. 2 but showing :an alternate form of contact element;

FIG. 7 is similar to FIG. 3 showing the same alternate form of contact element shown in FIG. 6;

FIG. 8 is a corner view similar to FIG. 4 showing the "alternate form of contact strip;

FIG. 9 is a view similar to alternate form of strip;

FIG. 10 is a view, in section, along the line X-X of FIG. 1 showing the latch construction; and

FIGS. 11 and 12 are views along the lines XI-XI and of FIG. 10.

In describing the preferred embodiment of my invention as illustrated in the drawing, specific terminology has been resorted to for the sake of clarity. However, it is not my intention to be limited to the specific terms so sebe understood that each specific term that of FIG. 5 showing the similar manner to accomplish a similar purpose.

Referring now to the drawing, the three non-hinged edges at least of the door 10, namely, the top edge 12,

the bottom edge 14, and the non-hinged vertical edge 16,

are stepped downwardly and inwardly from the outer surface 18 to the inner surface 19 of the door, in the manner seen in FIGS. 2 and 3.

The door casing 20 has a corresponding stepped construction on each of its three corresponding sides, namely, the overhead 22, the sill 24 and the jamb 26. If desired, the fourth or hinged edge 28 of the door, and the corresponding edge 29 of the door casing, may also be of stepped construction, as shown in FIG. 7.

The door 10 and door casing 20 (and also the other 2 portions of the enclosure to which the door 10 provides access) are fabricated of metal having good electrical conducting properties, such as steel, or a non-fenrous metal, such as aluminum or copper.

Door 10 may be supported on any suitable form of metal hinge of good electrical conductivity. In FIGS. 1 and 3, a piano hinge 15 is shown, while in FIG. 7 a flat hinge 17 is illustrated. Good electrical con-tact between the door 10 and the door casing 20 is provided by the hinge.

Alternate portions of the stepped edge of the door, and also of the casing, function as abutment surfaces. The other alternate portions are surfaces which, if contact is made at all, slidingly and frictionally engage during opening and closing of the door. In the drawing, the inwardly facing abutment surfaces of the door are identified by the reference numeral 30, while the corresponding outwardly facing abutment surfaces of the casing are identified by reference numeral 36. The other surfaces (those which are subject to sliding frictional engagement during opening and closing of the door) are not identified by any reference numeral, being plainly identifiable in the drawing.

The abutment surfaces 30 of each of the three stepped door edges (or of the four stepped edges if the hinged edge is also stepped) are, in the embodiment illustrated FIGS. 2, 3, and 4, provided with a flattened tubular metal strip 32 of resilient material of good electrical conductivity, such as steel or copper, a piece of the strip being shown in FIG. 5. Strip 32, which may be braided or woven steel mesh or cloth, is soldered, or cemented, or otherwise secured to the abutment surfaces 30 of the stepped door edges, as seen in cross section in FIGS. 2 and 3. In the course of such soldering or cementing, the opposing flattened central portions 33 of the tubular metal strip 32 also become soldered, cemented, or otherwise secured to each other, as seen clearly in FIG. 5, thereby forming the beaded edge portions 34 which protrude in the direction of the abutment portions 36 of the stepped edges of the door casing 20.

Alternatively, the abutment surfaces 30 of the stepped door edges may be provided with an S-shaped or reversecur ve tension strip 38, shown in FIG. 9, and seen in cross section in FIGS. 6 and 7. As in the case of the strip of tubular metal cloth shown in FIG. 5, the strip of FIG. 9 is of resilient metal, of good electrical conductivity, such as steel or copper. The raised edge 39 of strip 38 is preferably provided with slots or notches 40, as shown, to assist the recovery action of the resilient strip.

Referring now to FIGS. 1012, there is illustrated a pull-in type of door latch mechanism which may preferably be employed with my stepped door construction to assure good contact between the abutting surfaces 30 and 36 of the stepped door and casing. The latch mechanism shown in FIGS. 10-12 is operated by turning rotationally one of the door handles, outside handle 49 or inside handle 50. When either one is turned rotationally, a wedge actuator plate 51 is caused to move rotationally, thereby to move in one direction or the other (according to the direction of rotation of plate 51) a horizontal wedge bar 54 and a pair of vertical wedge bars 57, 67 (57 being the upper wedge bar and 67 the lower wedge bar).

The door handles 49, '50 are connected to the wedge actuator plate 51 by way of a shaft 56 which extends through the door 10 and is supported by a bushing 59. Handles 49, 50 are fixed to shaft 56; the wedge actuator plate 51 is also fixed to the shaft 56, as by being welded thereto. The wedge bars 54, 57, 67 are pivotly secured to the actuator plate 51, as shown in FIG. 12. Rotation of the actuator plate 51 in one direction causes the wedge bars 54, 57, 67 to retract from an extended position; rotation in the opposite direction causes the wedge bars to assume an extended position.

Wedge bars 57, 67 extend vertically from the actuator plate 51 in an upward and downward direction respectively. Wedge bar 54 extends horizontally. Each bar is of such length as to extend to the step of the door but not beyond when the actuator plate 51 is in the fully retracted position. (In FIG. 12, the actuator plate 51 is shown in dot-and-dash lines in a partially retracted position.) Each bar extends a short distance beyond the step of the door and into the door casing 2@ when the actuator plate 51 is in the fully extended position (shown in solid lines in FIG. 12).

The ends of each of the wedge bars 54, 57, 67 are tapered or wedge-shaped, as shown in FIG. 10. Mounted in the door casing 20, at the three locations occupied by the end portions of the three wedge bars when fully extended, are tapered wedge blocks 55 for receiving the tapered ends of the wedge bars. Hold down plates 52, 62 are provided for the vertical bars, and hold down plate 53 is provided for the horizontal bar, for guiding the wedge bars during movement and for receiving the thrust or load which is placed upon the bars when the door is being closed and latched.

In operation, when the door v10 is closed and latched, the wedging or camming action of the pull-in latch mechanism just described, assures good electrical contact between the abutting surfaces 30, 36 of the door and casing, respectively, by way of the resilient metal strips 32 (or 33). It is, accordingly, substantially immaterial whether there is or is not close physical contact between those portions of the steps of the door and casing which are at right angles to the abutting surfaces and which, if contact is made, are slidingly and frictionally engaged. In 'FIGS. 2 and 6, contact between all slidingly and engaged surfaces is shown but this is not necessary or even desirable. In FIGS. 3 and 7, the innermost surfaces are shown separated by a substantial spacing, at least some separation being necessary in order to permit the innermost corner of the door to swing along the arcuate path which is the locus of the moving door corner relative to the door hinge. Such spacing is of little consequence, however, insofar as effective shielding is concerned, since a low resistance electrical path between the door and the casing is provided through the resilient strips which connect electrically the abutting surfaces of the door and casing. It is at these abutting surfaces that good contact is assured by the three-point pull-in latch mechanism, described above.

It will be understood from what has been said that the door 10 is adapted to be closed and opened without sticking and binding. It will also be seen that, insofar as effective shielding is concerned, it is of little consequence if, during use, the door becomes misaligned, so long as there is good electrical contact between the abutting surfaces of the stepped door and easing.

While the preferred embodiments of this invention have been described in some detail, it will be obvious to one skilled in the art that various modifications may be made without departing from my invention as hereinafter claimed.

Having thus described my invention, I claim:

1. A doorway construction for a radio-frequency shielded enclosure comprising: a hinged door and a door casing, each of material of good electrical conductivity, three edges of said door being stepped downwardly and inwardly from the outer toward the inner surface of said door, forming a plurality of inwardly facing abutment surfaces, the corresponding edges of said door casing having corresponding stepped construction forming corresponding outwardly facing abutment surfaces for receiving the abutment surfaces of said door; compressible strips of resilient metal of good electrical conductivity secured to said abutment surfaces of said stepped door edges and protruding therefrom in the direction of said door casing for making an electrical contact with the corresponding abutment surfaces of said door casing when said door is in its closed position; and a three-point pull-in latch mechanism for said door for assuring close contact between said compressible strips of metal and said abutment surfaces, said latch mechanism including, a rotatable door-handle shaft, three wedge bars mounted in said door between the inner and outer surfaces thereof and extendible beyond non-abutment surfaces of the different edges of said door in response to the rotation of said door-handle shaft, and three tapered wedge blocks mounted at different edges of said door casing forming tapered recesses in non-abutting surfaces of different edges of said door casing for receiving said wedge bars when extended for camming said door into close engagement with said casing.

2. A doorway construction for a radio-frequency shielded enclosure comprising: a hinged door and a door casing, each of material of good electrical conductivity, at least three edges of said door being stepped downwardly and inwardly from the outer toward the inner surface of said door forming at least two inwardly facing abutment surfaces, at least the three corresponding edges of said door casing having corresponding stepped construction forming corresponding outwardly facing abutment surfaces for receiving the abutment surfaces of said door; and strips of resilient metal of good electrical conductivity secured to each of said abutment surfaces of said stepped door edges and protruding therefrom in the direction of said abutment surfaces of said door casing for making pressure contact with the corresponding abutment surfaces of said door casing when said door is in its closed position.

3. A doorway construction as claimed in claim 2 characterized in that said strips of metal have a reverse curve cross section with notches along the unsecured edge.

4. A doorway construction as claimed in claim 2 characterized in that said strips of metal are of oval tubular construction, the opposing central portions being secured to each other forming beaded edges.

5. A doorway construction as defined in claim 4 wherein the three stepped edges of the door comprise the edges forming the top, bottom, and opening end of said door.

References Cited in the file of this patent UNITED STATES PATENTS 398,611 Hall Feb. 26, 1889 2,757,225 Dunn July 31, 1956 2,853,541 Lindgren Sept. 23, 1958 OTHER REFERENCES Publication I, Suppressing Radio Interference with Metex Shielding Products, published by the Metal TeX- tile Corporation, Electronics Division, Roselle, NJ. (page 11 relied on).

Publication II, ACE Shielding Enclosures published by Ace Engineering and Machine Co., 3644 N. Lawrence Street, Philadelphia 40, Pa. (page 7 relied on).

Disclaimer 3,055,969.-0Zaren0e Randall Sehaller, J12, Philadelphia, Pa. DOOR OON- STRUOTION FOR SHIELDED ROOM. Patent dated Sept. 25, 1962. Disclaimer filed July 26, 1968, by the assignee, Ace E ngz'neering and Machine Company, Inc.

Hereby enters this disclaimer to claims 2, 3 and 5 of said patent.

[Ofiicz'al Gazette October 8, 1.968.]

Disclaimer 3,o55,e9. 0zm-eme Randall SohaZZer, J12, Philadelphia, Pa. DOOR CON- STRUCTION FOR SHIELDED ROOM. Patent dated Sept. 25,

1962. Disclaimer filed July 26, 1968, by the assignee, Ace Engineev'z'ng and Machine Company, Inc.

Hereby enters this disclaimer to claims 2, 3 and. 5 of said patent.

[Ofiicial Gazette October 8, 1.968.] 

